Porth Yr Ogof cave in South Wales

So far I went only to the main entrance, but I will explore more when I have time.

25 FEB 2019, Brecon Beacons national park

More info:

Porth Yr Ogof (translated as the gateway to the cave) boasts the largest entrance of any cave in Wales at over 17 m wide and almost 5 m tall. Porth Yr Ogof was once operated as a showcave, but is now managed by the Brecon Beacons National Park Authority on a 999 year lease. A managed pay and display car park adjoins a BBNPA visitor centre that is generally manned by a warden. The maze of passages with multiple entrances and easy access has made this the most popular cave in South Wales for outdoor activity groups. The cave is estimated to have over 30,000 visitors per year. Length 2,200mAltitude 229m

The cave has 15 different entrances leading to over a mile of accessible underground passageways which makes this very popular with outdoor groups to introduce people to caving. In normal weather conditions a dry rocky river bed leads up to the main entrance to the cave, but following rain this may quickly become a raging torrent as the Afon Mellte (the Lightning River) lives up to its name and quickly makes the cave inaccessible. Care must be taken in wet weather. Another sinister danger in this cave is the resurgence pool, where the water leaving the cave is forced through a narrow passage, in doing so it has scoured out a 7 m deep pool with underwater ledges, this coupled with the strong undercurrents created by the flow of the water has made this the most dangerous location in any British cave. In this short section of cave 10 people have drowned all within the sight of daylight, the dangers here should not be underestimated, signs in the cave before the pool warn of the danger and direct you to alternative exits.